From: Oleg Nesterov <oleg@redhat.com>
To: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Cc: jeremy@goop.org, kvm@vger.kernel.org, peterz@infradead.org,
virtualization@lists.linux-foundation.org,
paul.gortmaker@windriver.com, hpa@zytor.com, ak@linux.intel.com,
a.ryabinin@samsung.com, x86@kernel.org, borntraeger@de.ibm.com,
mingo@redhat.com, xen-devel@lists.xenproject.org,
paulmck@linux.vnet.ibm.com, riel@redhat.com,
konrad.wilk@oracle.com, dave@stgolabs.net,
sasha.levin@oracle.com, davej@redhat.com, tglx@linutronix.de,
waiman.long@hp.com, linux-kernel@vger.kernel.org,
pbonzini@redhat.com, akpm@linux-foundation.org,
torvalds@linux-foundation.org
Subject: Re: [PATCH V3] x86 spinlock: Fix memory corruption on completing completions
Date: Thu, 12 Feb 2015 15:02:48 +0100 [thread overview]
Message-ID: <20150212140248.GA11050@redhat.com> (raw)
In-Reply-To: <1423741647-2156-1-git-send-email-raghavendra.kt@linux.vnet.ibm.com>
Damn, sorry for noise, forgot to mention...
On 02/12, Raghavendra K T wrote:
>
> +static inline void __ticket_check_and_clear_slowpath(arch_spinlock_t *lock,
> + __ticket_t head)
> +{
> + if (head & TICKET_SLOWPATH_FLAG) {
> + arch_spinlock_t old, new;
> +
> + old.tickets.head = head;
> + new.tickets.head = head & ~TICKET_SLOWPATH_FLAG;
> + old.tickets.tail = new.tickets.head + TICKET_LOCK_INC;
> + new.tickets.tail = old.tickets.tail;
> +
> + /* try to clear slowpath flag when there are no contenders */
> + cmpxchg(&lock->head_tail, old.head_tail, new.head_tail);
> + }
> +}
...
> +clear_slowpath:
> + if (TICKET_SLOWPATH_FLAG)
> + __ticket_check_and_clear_slowpath(lock, inc.head);
I think you can remove this "if (TICKET_SLOWPATH_FLAG)" check. If it is
defined as zero, gcc should optimize out the code under "if (head & 0)".
But this is purely cosmetic and subjective, feel free to ignore.
Oleg.
next prev parent reply other threads:[~2015-02-12 14:02 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-12 11:47 [PATCH V3] x86 spinlock: Fix memory corruption on completing completions Raghavendra K T
2015-02-12 13:37 ` Oleg Nesterov
2015-02-12 14:21 ` Raghavendra K T
2015-02-12 13:50 ` Oleg Nesterov
2015-02-12 14:23 ` Raghavendra K T
2015-02-12 14:02 ` Oleg Nesterov [this message]
2015-02-12 14:25 ` Raghavendra K T
2015-02-12 15:00 ` Peter Zijlstra
2015-02-12 15:28 ` Raghavendra K T
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